It depends on what part you want. If it's a student, sing one of their bigger lines. (ie, if you're going for Grantaire, the bit from ABC Cafe, "I am agog, I am aghast", etc...or if you're going for a gang member from Thenardier's gang, a line from "Attack On Rue Plumet", etc.) You can audition for more than one role, as well. Just check our cast list to see who's still needed.